The present invention relates to a process for the preparation of a supported olefin polymerization catalyst composition, comprising a support, a metallocene, and an aluminoxane. The invention also relates to a supported olefin polymerization catalyst composition which has been prepared according to said process and to the use of such a supported olefin polymerization catalyst composition for the polymerization of at least one olefin.
In many olefin polymerization processes using a single site catalyst, it is desirable to support the catalyst on a carrier or support. Usually such supported catalyst compositions include a metallocene and an aluminoxane supported on an inorganic oxide carrier such as silica and/or alumina.
For example, WO 96/00243 describes a method for producing a supported catalyst composition by mixing a bridged bis-indenyl metallocene and an aluminoxane in a solvent to form a solution, and then combining the solution and a porous support, whereby the total volume of the solution is less than that at which a slurry is formed. A typical support used was previously heated silica MS 948 (Grace) and a typical aluminoxane used was gel-free methyl aluminoxane (MAO), both of which were used in all of the examples.
According to S. Srinvasa Reddy, Polymer Bulletin, 36 (1996) 317-323, the ethylene polymerization activity of tetraisobutyldialuminoxane cocatalyst was clearly lower than the activity of methylaluminoxane cocatalyst. This reflects the previous general opinion, that only methyl aluminoxane as a cocatalyst gave satisfactory ethylene polymerization catalyst activities.
The purpose of the present invention is to replace MAO as an olefin polymerization procatalyst. More specifically, the present invention aims at providing an olefin polymerization catalyst composition including a higher C2-C10 alkyl aluminoxane, which has commercially satisfactory activity when producing olefin homopolymers and copolymers. A further goal of the present invention is a supported olefin polymerization catalyst composition for use in gas phase, slurry phase or liquid/solution phase polymerizations.
The above mentioned purposes of the invention have now been realized by a novel process for the preparation of a supported olefin polymerization catalyst composition, comprising a support, a metallocene, and an aluminoxane. The claimed process is mainly characterized by contacting a support comprising a solid compound which is one of an aluminium oxide, a mixed aluminium oxide such as silica-alumina, an aluminium salt, a magnesium halide or a C1-C8 alkoxy magnesium halide, in any order with at least
a) an organometallic compound of the general formula (1):
R1MXvxe2x88x921xe2x80x83xe2x80x83(1)
wherein each R is the same or different and is a C1-C10 alkyl group; M is a metal of Group 1, 2, 12 or 13 of the Periodic Table (IUPAC 1990); each X is the same or different and one of a halogen atom, a hydrogen atom, a hydroxyl radical or a C1-C8 hydrocarbyloxy group; 1 is 1, 2 or 3; v is the oxidation number of the metal M,
b) a metallocene of the general formula (2):
(CpY)mMxe2x80x2Xxe2x80x2nZoxe2x80x83xe2x80x83(2)
wherein each CpY is the same or different and is one of a mono- or polysubstituted, fused or non-fused, homo- or heterocyclic cyclopentadienyl, indenyl, tetrahydroindenyl, fluorenyl, or octahydrofluorenyl ligand, the ligand being covalently substituted at its cyclopentadienyl ring with at least one substituent Y which is one of a xe2x80x94ORxe2x80x2, xe2x80x94SRxe2x80x2, xe2x80x94NRxe2x80x22, xe2x80x94C(H or Rxe2x80x2)xe2x95x90, or xe2x80x94PRxe2x80x22 radical, each Rxe2x80x2 being the same or different and being one of a C1-C16 hydrocarbyl group, a tri-C1-C8 hydrocarbyl silyl group or a tri-C1-C8 hydrocarbyloxy silyl group; Mxe2x80x2 is a transition metal of Group 4 of the Periodic Table and bound to the ligand CpY at least in an xcex75 bonding mode; each Xxe2x80x2 is the same or different and is one of a hydrogen atom, a halogen atom, a C1-Ck8 hydrocarbyl group, a C1-C8 hydrocarbylheteroatom group or a tri-C1-C8 hydrocarbylsilyl group or two Xxe2x80x2 form a ring with each other; Z is a bridge atom or group between two CpY ligands or one CpY ligand and the transition metal Mxe2x80x2; m is 1 or 2; o is 0 or 1; and n is 4xe2x88x92m if there is no bridge Z or Z is a bridge between two CpY ligands or n is 4xe2x88x92mxe2x88x92o if Z is a bridge between one CpY ligand and the transition metal Mxe2x80x2, and
c) an aluminoxane of the following general formulas (3): xe2x80x83(OAlRxe2x80x3)pxe2x80x83xe2x80x83(3 general)
wherein each Rxe2x80x3 and each Rxe2x80x2xe2x80x3 is the same or different and is a C2-C10 alkyl group; and p is an integer between 1 and 40,
and recovering said supported olefin polymerization catalyst composition.
By mono- or polysubstituted is meant that, in addition to said substituent Y, there may optionally be other substituents at the rings at said ligands CpY.
By fused or non-fused is meant that any ring at said ligands may be fused or non-fused, i.e. have at least two atoms in common, with at least one further ring.
By homo- and heterocyclic is meant that any ring of said ligands may have only carbon ring atoms (homo- or isocyclic) or may have other ring atoms than carbon (heterocyclic).
It has thus been realized that a C2-C10 alkyl aluminoxane (i.e. a non-methyl aluminoxane) can successfully be used as the cocatalyst, if a support comprising an aluminium pure oxide, mixed oxide or salt, or a magnesium halide, is first treated with a metal alkyl compound and then activated with a metallocene having a xe2x80x94ORxe2x80x2, xe2x80x94SRxe2x80x2, xe2x80x94NRxe2x80x22, xe2x80x94C(H or Rxe2x80x2)xe2x95x90, or xe2x80x94PRxe2x80x22 substituent at the cyclopentadienyl ring.
According to non-limiting model, said electron pair of double bond substituents at the cyclopentadienyl ring delocalize it""s negative charge and help to ionise the metallocene, whereby the transition metal M becomes more cationic (electron density deficient). By combining this with special metyl alkyl treatment of acidic surfaces (like alumina, aluminium phosphate, silica-alumina, etc.) the cationisation can be enhanced. This improves the catalytic interaction between the metallocene and the aluminoxane and enables the use of higher aluminoxanes like those of the above formula (3).
Generally, said support can be contacted with compounds a), b) and c) in any order. Thus, the support can e.g. be impregnated with a solution of the three compounds a), b) and c), first with compound a) and then with a solution containing compound b) and compound c), or preferably, contacting said support at first with
a) said organometallic compound of the general formula (1), then with
b) said metallocene of the general formula (2), and after that with
c) said aluminoxane of the general formulas (3).
According to one embodiment of the invention, the contacting of the support with compounds a), b) and c) takes place by contacting the support with one or several solutions of the compounds. The support can, for example, be contacted with a solution of said organometallic compound (1) and thereafter with a solution containing said metallocene (2) and said aluminoxane (3). In a preferable embodiment of the invention, the contacting takes place by
a1) contacting said support with a solution of said organometallic compound (1), and removing the supernatant from the contacting product,
b1) contacting the product of step a1) with a solution of said metallocene (2), and removing the supernatant from the contacting product, and
c1) contacting the product of step b1) with a solution of said aluminoxane (3), and removing the supernatant from the contacting product.
When contacting said support with compounds a), b) and c) in liquid form such as the form of a solution, a slurry or a non-slurry contacting product can be formed. However, it is preferable to impregnate the support with a liquid, the volume of which is less than at which a slurry is formed. This means that the volume of said liquid is less than or approximately equal to the volume of the support pores.
The support used in the process of the present invention is a support comprising a solid compound which is one of a pure aluminiumoxide, a mixed aluminiumoxide, an aluminium salt, a magnesium halide or a C1-C8 alkoxy magnesiumhalide. A typical aluminium salt is aluminium phosphate AlPO4. According to preliminary experiments pure silica did not give high activity olefin polymerization catalysts when combined with a C2-C10 alkyl aluminoxane according to formula (3) and a metallocene according to formula (2). In the claimed process, however, the support comprising, i.e. consisting of, containing, or having carried thereupon said solid compound, gives high activity with compounds (2) and (3). It is believed (non-limiting) that the supports listed above are more acidic than silica and, thanks to their nature as Lewis-acids, contribute to the activation of said metallocenes and said higher aluninoxanes. The material carrying said compound can be any inert particulate material, including silica. The most preferable support comprises a porous aluminium oxide, most preferably alumina, which has been heated to a temperature between 100-1000xc2x0 C. The aluiminium oxide, preferably the calcined alumina, is preferentially in the form of, or deposited on, particles having a diameter of between 10-500 xcexcm, most preferably between 20 and 200 xcexcm. The specific surface area of the aluminium oxide or calcined alumina is according to one embodiment of the invention between 50 and 600 m2/g, preferably between 100 and 500 m2/g. The average pore volume is usually between 0.5 and 5.0 ml/g, preferably between 1.0 and 2.5 ml/g. The average pore diameter is for example 100-500 xc3x85, preferably approximately 200 xc3x85.
According to the process of the present invention, the support is contacted with
a) an organometallic compound of the general formula (1):
R1MXvxe2x88x921xe2x80x83xe2x80x83(1)
wherein each R is the same or different and is a C1-C10 alkyl group; M is a metal of Group 1, 2, 12 or 13 of the Periodic Table; each X is the same or different and one of a halogen, a hydrogen atom, a hydroxyl radical or a C1-C8 hydrocarbyloxy group; 1 is 1, 2 or 3; and v is the oxidation number of the metal M.
According to a non-limiting theoretical model, the organometallic compound alkylates said solid compound of the support, which in turn alkylates and activates the metal of the metallocene. This is then reflected in the successful use of otherwise poorly active higher aluminoxanes.
The C1-C10 alkyl group R of formula (1) is preferably a C1-C6 alkyl group and most preferably a C1-C4 alkyl group. When defining M by means of the Groups and Periods of the Periodic Table, the new numbering system is used (IUPAC 1990). Preferred metals M are those of Periods 1-4 of the Periodic Table.
If occuring, X of formula (1) is a halogen atom, a hydrogen atom, a hydroxyl radical or a hydrocarbyloxy group. According to one preferable embodiment of the invention, said support is contacted with
a) said organometallic compound of the general formula (1), which is one of a C1-C10 alkyl lithium, a C1-C10 dialkyl magnesium, or a C1-C10 trialkyl aluminium, and most preferably is a C1-C6 trialkyl aluminium such as trimethyl aluminium (TMA). When contacting said support with said organometallic compound, it is preferable if the organometallic compound of the formula (1) is immersed or dissolved in a hydrocarbon medium, most preferably a C4-C10 hydrocarbon medium. The weight ratio between the added organometallic compound, calculated as trimethyl aluminium, and the support depends on the surface area, pore volume and diameter, surface hydroxyl number and type. According to one embodiment it is between 0.1 and 10, more preferably between 0.2 and 2 and most preferably between 0.3 and 1.5. After the contacting step the remaining unreacted organometallic compound is preferably removed together with the possible hydrocarbon medium, followed by optional washing steps.
According to the process of the present invention said support is contacted with
b) a metallocene of the general formula (2). It is preferred that the metallocene of the general formula (2) as group Rxe2x80x2 of said substituent Y has a tri-C1-C8 hydrocarbyl silyl or tri-C1-C8 hydrocarbyloxy silyl group. Especially suitable tri-C1-C8 hydrocarbylsilyl groups are those capable of xcfx80 interaction with said O, S, N, or P atoms of Y. Most preferred are tri-C1-C8 alkyl silyl groups, wherein at least one of the C1-C8 alkyls is a branched C3-C8 alkyl group such as isopropyl, isobutyl, sec-butyl, tert-butyl, isoamyl, sec-amyl, tert-amyl, isohexyl, sec-hexyl, or tert-hexyl. Cyclic alkyls and aryls are also preferred groups of the silicone atom.
According to one embodiment of the invention there is only one ligand CpY in the metallocene of formula (2), which preferably is bound to the transition metal Mxe2x80x2 by both said xcex75 bond and by a bridge Z preferably containing a heteroatom.
However, said metallocene of the general formula (2) has most preferably two ligands CpY, i.e. m is 2. According to a still more preferred embodiment, the two CpY ligands are bridged with each other by a bivalent atom or group Z having at least one chain atom which is one of a carbon, silicon, oxygen, sulphur, nitrogen, or phosphorous atom. Most preferably, the metallocene of the general formula (2) has m=2, whereby Z is an ethylene or a silylene bridge.
The transition metal Mxe2x80x2 of group 4 of the Periodic Table in the general formula (2) is Ti, Zr or Hf, more preferably Zr or Hf, and most preferably Zr. The valency or oxidation number of Mxe2x80x2 is 4.
In the definition of Y above, a heteroatom means xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, 
or 
The preferable atom or group Xxe2x80x2 of said metallocene of formula (2) is a halogen atom and/or a C1-C8 hydrocarbyl group. Most preferably, Xxe2x80x2 is chlorine and/or methyl. The number of Xxe2x80x2 atoms or groups, i.e. xe2x80x9cnxe2x80x9d, is preferably 1-3, most preferably 2, considering the limitation given above for the case when Z is a bridge between CpY and Mxe2x80x2.
Particularly preferred metallocenes of the general formula (2) are compounds of following structural formula (4). 
wherein Y1 and Y2 are the same or different and are one of a hydrogen atom, a halogen atom, an acyl group, an acyloxy group, a C1-C10 hydrocarbyl group, a xe2x80x94ORxe2x80x2, xe2x80x94SRxe2x80x2, xe2x80x94NRxe2x80x2, xe2x80x94C(H or Rxe2x80x2)xe2x95x90, or xe2x80x94PRxe2x80x22 radical, Rxe2x80x2 being one of a C1-C16 hydrocarbyl group or a tri-C1-C8-hydrocarbylsilyl group, provided that at least one of Y1 and Y2 is one of said xe2x80x94ORxe2x80x2, xe2x80x94SRxe2x80x2, xe2x80x94NRxe2x80x2, xe2x80x94C(H or Rxe2x80x2)xe2x95x90, or xe2x80x94PRxe2x80x22 radicals; Z is a bivalent atom or group having at least one chain atom which is one of a carbon, silicon, oxygen, sulphur, nitrogen or phosphorus atom, preferably 1-4 carbon and/or silicon chain atoms; each Rv is the same or different and is one of a hydrogen atom, a halogen atom, a C1-C10 hydrocarbyl or ring constituent, or a C1-C10 hydrocarbyloxy group. Mxe2x80x2 is one of Ti, Zr or Hf; and X1xe2x80x2 and X2xe2x80x2 are the same or different and are one of a halogen atom and a C1-C8 hydrocarbyl group. The analogous 4,5,6,7-tetrahydroindenyl derivatives are also useful in the invention.
A representative metallocene of the formula (2) is ethylene-bis(2-tert-butyldimethyl-siloxyindenyl)zirconium dichloride.
When using chiral metallocenes, they can be used as a racemate for the preparation of highly isotactic xcex1-olefin polymers. The pure R or S form of said metallocene can also be used, e.g. for the production of optically active polymer.
The metallocene of the general formula (2) is usually prepared by a process involving repeated deprotonations/metallizations of the aromatic ligands and introduction of the bridge Z atom or atoms as well as the central atom by their halogen derivatives. The preparation of the said metallocene of the general formula (2) can e.g. be carried out according to a J. Organometallic Chem. 288 (1958) 63-67 and EP-A-320762, both herewith incorporated by reference.
The most preferred metallocenes of the general formula (2), wherein Y is a tri-C1-C8 hydrocarbylsiloxy group, is preferably prepared as follows:
The catalyst compounds according to the invention can be prepared from 2-indanone. This compound can be reacted in a suitable solvent with a base and a chlorosilane to form 2-siloxyindene with a yield of over 80%. Suitable solvents are for example dimethylformamide (DMF) and tetrahydrofurane (THF). Suitable bases are for example imidazole and triethylamine (TEA). Suitable chlorosilanes are for example tert-butyldimethylchlorosilane, t-hexyldimethylchlorosilane and cyclohexyldimethylchlorosilane. The reaction takes place according to the following reaction scheme (II): 
According to one embodiment of the invention 2-tert-butyldimethylsiloxyindene is reacted first with butyllithium and then with dimethyl dichlorosilane (Me2SiCl2) to form dimethylsilylbis(2-tert-butyldimethylsiloxyindene). Butyllithium can be replaced with methyllithium, sodium hydride or potassium hydride. Likewise dimethyl dichlorosilane can be replaced with any dialkyl or diarylsilane. Silicon can be replaced with germanium.
Dimethylsilylbis(2-tert-butyldimethylsiloxyindene) can be reacted with butyllithium, which gives the corresponding bislithium salt. This product can be reacted with zirconium tetrachloride to yield dimethylsilylbis(2-tert-butyldimethylsiloxyindenyl)zirconium dichloride as a mixture of the racemic and meso diastereomers. Butyllithium may be replaced as described earlier. Zirconium tetrachloride can be replaced with titanium tetrachloride or hafnium tetrachloride to give the corresponding titanium and hafnium complexes. The reactions take place according to the following reaction schemes (III-IV): 
According to another embodiment of the invention 2-tert-butyldimethylsiloxyindene is reacted first with butyllithium and then with dibromoethane to form bis(2-tert-butyldimethylsiloxyindenyl)ethane. This compound can be reacted with two equivalents of butyllithium, which gives the corresponding bislithium salt. This can then be reacted with zirconium tetrachloride to yield ethylenebis(2-tert-butyldimethylsiloxyindenyl)zirconium dichloride. The racemic diastereomer of the latter is formed in great excess and is easily separated from the meso isomer by fractional crystallization. Catalytic hydrogenation of racemic ethylenebis(2-tert-butyldimethylsiloxyindenyl)zirconium dichloride yields the corresponding tetrahydroindenyl complex. The reaction takes place according to the following reaction scheme (V): 
In the reactions above butyllithium may be replaced as described earlier. Zirconium tetrachloride can be replaced with titanium tetrachloride or hafnium tetrachloride to give the corresponding titanium and hafnium complexes.
According to still another embodiment of the invention 2-t-hexyldimethylsiloxyindene is reacted first with butyllithium and then with dibromoethane to form bis(2-t-hexyldimethylsiloxyindenyl)ethane. This compound can be reacted with two equivalents of butyllithium which gives the corresponding bislithium salt. This can then be reacted with zirconium tetrachloride to yield ethylenebis(2-t-hexyldimethylsiloxyindenyl)zirconium dichloride. The racemic diastereomer of the latter is formed in great excess and is easily separated from the meso isomer by fractional crystallization. The reaction takes place according to the following reaction scheme (VI): 
In the reactions above butyllithium may be replaced as described earlier. Zirconium tetrachloride can be replaced with titanium tetrachloride or hafnium tetrachloride to give the corresponding titanium and hafnium complexes. Hydrogenation of ethylenebis(2-t-hexyldimethylsiloxyindenyl)zirconium dichloride yields the corresponding tetrahydroindenyl complex.
Illustrative but non-limiting examples of the preferable compounds used according to the invention are, among others, racemic and meso dimethylsilylbis(2-tert-butyldimethylsiloxyindenyl)zirconium dichloride, racemic and meso diphenylsilylbis(2-tert-butyldimethylsiloxyindenyl)zirconium dichloride, racemic and meso dimethylsilylbis(2-t-hexyldimethylsiloxyindenyl)zirconium dichloride, racemic and meso diphenylsilylbis(2-t-hexyldimethylsiloxyindenyl)zirconium dichloride, racemic and meso dimethylsilylbis(2-cyclohexyldimethylsiloxyindenyl)zirconium dichloride, racemic and meso dimethylsilylbis(2-cyclohexyldimethysiloxyindenyl)zirconium dichloride, racemic and meso dimethylsilylbis(2-2-tert-butyldiphenylsiloxyindenyl)zirconium dichloride, racemic and meso diphenylsilylbis(2-tert-butyldiphenylsiloxyindenyl)zirconium dichloride, racemic and meso dimethylsilylbis(2-tert-butyldimethylsiloxy-4,5,6,7-tetrahydroindenyl)zirconium dichloride, racemic and meso diphenylsilylbis(2-tert-butyldimethylsiloxy-4,5,6,7-tetrahydroindenyl)zirconium dichloride, racemic and meso dimethylsilylbis(2-t-hexyldimethylsiloxy-4,5,6,7-tetrahydroindenyl)zirconium dichloride, racemic and meso diphenylsilylbis(2-t-hexyldimethylsiloxy-4,5,6,7-tetrahydroindenyl)zirconium dichloride, racemic and meso dimethylsilylbis(2-cyclohexyldimethylsiloxy-4,5,6,7-tetrahydroindenyl)zirconium dichloride, racemic and meso diphenylsilylbis(2-cyclohexyldimethylsiloxy-4,5,6,7-tetrahydroindenyl)zirconium dichloride, racemic and meso dimethylsilylbis(2-tert-butyldiphenylsiloxy-4,5,6,7-tetrahydroindenyl)zirconium dichloride, racemic and meso diphenylsilylbis(2-tert-butylphenylsiloxy-4,5,6,7-tetrahydroindenyl)zirconium dichloride, rac-ethylenebis(2-tert-butylmethylsiloxyindenyl)zirconium dichloride, racemic and meso ethylenebis(2-t-hexyldimethylsiloxyindenyl)zirconium dichloride, racemic and meso ethylenebis(2-cyclohexyldimethylsiloxyindenyl)zirconium dichloride, racemic and meso ethylenebis(2-tert-butyldiphenylsiloxyindenyl)zirconium dichloride, rac-ethylenebis(2-tert-butyldimethylsiloxy-4,5,6,7-tetrahydroindenyl)zirconium dichloride, racemic and meso ethylenebis(2-cyclohexyldimethylsiloxy-4,5,6,7-tetrahydroindenyl)zirconium dichloride, racemic and meso ethylenebis(2-tert-butyldiphenylsiloxy-4,5,6,7-tetrahydroindenyl)zirconium dichloride and rac-ethylenebis(2-t-hexyldimethylsiloxyindenyl)zirconium dichloride. Titanium or hafnium can be used instead of zirconium in corresponding complexes.
When contacting said support, comprising a solid compound which is one of a pure aluminium oxide, a mixed aluminium oxide, an aluminium salt, a magnesium halide or a C1-C8 alkoxy magnesium halide, with
b) said metallocene of the general formula (2), the metallocene is preferably dissolved in a C4-C10 hydrocarbon solvent and most preferably in an aromatic hydrocarbon solvent such as toluene. As was said before, the metallocene hydrocarbons solution may also contain an alumoxane. The solution is then contacted with the support, which generally is porous.
It is also advantageous, if the total volume of the solution added to the support is less than the volume required to form a support slurry and, according to one embodiment, equal to or less than the pore volume of the support.
Although the amount of metallocene may very much e.g. due to the structure of the support, according to one embodiment of the present invention, the support is contacted with
b) said metallocene of the formula (2) at a molar to weight ratio between the metallocene and the support of between 0.001 to 0.50 mmol/g, more preferably 0.010 to 0.10 mmol/g, most preferably 0.02 to 0.08 mmol/g.
In the present process for the preparation of a supported olefin polymerization catalyst composition, the support is contacted with
c) an aluminoxane of the general formulas (3). Formulas (3) are general formulas including not only linear and cyclic compounds, but also aluminoxane compounds of cage and net structures. See e.g. Harlan, et. al., J. Am Chem. Soc., 117, (1995) p. 6466, the aluminoxane structures of which are enclosed by reference to disclose one embodiment of the invention.
The aluminoxane used in the process of the present invention is preferably an aluminoxane (3), wherein said Rxe2x80x3, and optionally said Rxe2x80x2xe2x80x3 is a C3-C10 alkyl group, more preferably an isopropyl, isobutyl, sec-butyl, tert-butyl, isoamyl, sec-amyl, tert-amyl, isohexyl, sec-hexyl or tert-hexyl group. The most preferred aluminoxane of the formula (3) is preferably an aluminoxane in which 2xe2x89xa6nxe2x89xa612, most preferably 4xe2x89xa6nxe2x89xa68. A suitable aluminoxane of the formula (3) is hexa(isobutylaluminiumoxane). The aluminoxane according to the present invention can be prepared analogously to or by modifying a variety of methods for preparing aluminoxane, non-limiting examples of which are described in U.S. Pat. Nos. 4,665,208, 4,952,540, 5,091,352, 5,206,199, 5,204,419, 4,874,734, 4,924,018, 4,908,463, 4,968,827, 5,308,815, 5,329,032, 5,248,801, 5,235,081, 5,157,137, 5,103,031, EP-A-0 561 476, EP-B1-0 279 586, EP-A-0 594 218 and WO 94/10180.
It is preferable to contact said support previous to, immediately before, or at the beginning of the olefin polymerization, with
c) an aluminoxane of formula (3) dissolved or immersed in a hydrocarbon solvent, most preferably a C4-C12 aliphatic hydrocarbon solvent such as hexane. When contacting said support with said organometallic compound of the formula (1), said metallocene of the formula (2), and said aluminoxane of the formula (3), the molar ratio between the aluminoxane aluminium metal and the metallocene transition metal Mxe2x80x2 in the catalyst composition is preferably between 20 and 500, more preferably 30 and 300 and most preferably between 40 and 200. Even more preferably, said ratio is between 80 and 200.
When preparing a supported olefin polymerization catalyst composition according to the present invention, the contacting product between the support, the organometallic compound of the general formula (1), the metallocene of the general formula (2) and the aluminoxane of the general formula (3) can be subjected to a prepolymerization with at least one olefin such as propylene and/or ethylene. The prepolymerizate is then recovered as said supported olefin polymerization catalyst composition.
In addition to the above described process for the preparation of a supported olefin polymerization catalyst composition, the present invention also relates to a supported olefin polymerization catalyst composition which has been prepared according to said described process. The invention also relates to a process for polymerizing at least one olefin by polymerizing in the presence of a supported olefin polymerization catalyst prepared according to the above described process. In the polymerization (homopolymerization and copolymerization) olefin monomers, such as ethylene, propylene, 1-butylene, isobutylene, 4-methyl-1-pentene, 3-methyl-1-butene, 4,4-dimethyl-1-pentene, vinylcyclohexene and their comonomers, can be used. Dienes and cyclic olefins can also be homo- or copolymerized. These xcex1-olefins and other monomers can be used both in the polymerization and prepolymerization of the claimed supported olefin polymerization catalyst composition.
The polymerization can be a homopolymerization or a copolymerization and it can take place in the gas, slurry or a solution phase. The claimed catalyst composition can also be used in high pressure processes. Said xcex1-olefins can be polymerized together with higher xcex1-olefins in order to modify the properties of the final product. Such higher olefins are 1-hexene, 1-octene, 1-decene, etc.